One case is presented in which there was radiographic evidence that pleural space fluid disappeared at the 15th day after pneumonectomy. Clinical course was uneventful and the space was refilled at the postoperative fifth month. This complication was probably due to the presence of small a bronchopleural fistula, in spite of the difficulty experienced in its demonstration. Conservative management is recommended with frequent clinical and radiographic observations, so that early surgical intervention may b~ undertaken if an overt bronchopleural fistula results.[KTCS 1979;2:93-96]